The semiconductor integrated circuit (IC) industry has experienced rapid growth. Continuing advances in semiconductor manufacturing processes have resulted in semiconductor device structures with finer features and/or higher degrees of integration. Functional density (i.e., the number of interconnected devices per chip area) has generally increased while feature size (i.e., the smallest component that can be created using a fabrication process) has decreased. This scaling-down process and increased density of devices generally provide benefits by increasing production efficiency and lowering associated costs.
The increased density of devices in integrated circuits has generally increased the amount of noise in various circuits, as has the combination of various types of circuitry such as logic and radio-frequency processing circuits. Noise can be detrimental in integrated circuits because it can compromise the integrity of a signal, which can in turn cause a loss of data or errors in logic or signal processing.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.